EP0526492A1 - Procede et appareil de controle d'un objet - Google Patents

Procede et appareil de controle d'un objet

Info

Publication number
EP0526492A1
EP0526492A1 EP91907804A EP91907804A EP0526492A1 EP 0526492 A1 EP0526492 A1 EP 0526492A1 EP 91907804 A EP91907804 A EP 91907804A EP 91907804 A EP91907804 A EP 91907804A EP 0526492 A1 EP0526492 A1 EP 0526492A1
Authority
EP
European Patent Office
Prior art keywords
wavelength
filter
radiation
diamond
diamonds
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP91907804A
Other languages
German (de)
English (en)
Other versions
EP0526492B1 (fr
Inventor
Martin Phillip Smith
Robin Wyncliffe Smith
Christopher Mark Tythebarn Cottage Welbourn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gersan Ets
Original Assignee
Gersan Ets
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gersan Ets filed Critical Gersan Ets
Publication of EP0526492A1 publication Critical patent/EP0526492A1/fr
Application granted granted Critical
Publication of EP0526492B1 publication Critical patent/EP0526492B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/87—Investigating jewels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65—Raman scattering

Definitions

  • the invention relates to examining or classifying an object by detecting the spectral properties of the object.
  • the invention is particularly, but not exclusively, concerned with, identifying gemstones such as diamonds, e. g. distinguishing diamonds from diamond-like simulants and distinguishing natural diamonds from synthetic diamonds.
  • WO 86/07457 discloses a method for distinguishing diamond from diamond like simulant, by visually detecting the Raman signal emitted from a specimen which is irradiated with suitable exciting radiation.
  • the Raman emission has two peaks, one on either side of the wavelength of the exciting radiation, termed the Stokes signal and the anti-Stokes signal.
  • the Stokes signal is much stronger than the anti-Stokes signal / but it is still very weak.
  • One of the problems ia that if a diamond-like simulant luminesces, it is very hard to discern the appropriate Raman peak against the luminescent background..
  • Diamond simulant comprises dense non-diamond material (eg. metal oxides, particularly zirconium dioxide) which has similar refractive properties to diamond.
  • Synthetic diamond actually comprises diamond material (ie. crystalline carbon) produced by an industrial process.
  • the first aspect of the invention provides a method of and apparatus for classifying an object as set out in Claims 1, 18, 46 or 47 and a method of and apparatus for examining an object as set out in Claims 22, 33, 42 or 43.
  • Preferred and/or optional features are set out in Claims 2 to 17, 19 to 21, 23 to 32 and 34 and 35.
  • the invention enables diamonds and other suitable gemstones to be examined and classified by operators with little scientific or technical training.
  • the object is irradiated with stimulating radiation and the emission/luminescence of the object is examined.
  • a laser that will cause Raman activation in the visible spectrum; a suitable Raman wavelength is about 552.4 nm which can be produced by an argon ion laser operating at 514.5nm, and in general terms the laser wavelength may lie between 450 nm and 1064 nm, but may be outside this range.
  • the signal detected will be markedly different, depending on whether the object or gemstone is say a diamond, or a diamond simulant which does not exhibit Raman emission at the correct wavelength, and does not luminesce, or a diamond simulant which luminesces. This is explained later with reference to the drawings.
  • a simple method of altering the band passed is by tilting the filter about an axis normal to its optical axis.
  • the cut-offs are most clearly defined when the filter is correctly orientated with its optical axis; as the filter is tilted, the centre of the band passed changes, and the band widens - this widening is not essential to the preferred embodiment of the invention, but is an incidental effect.
  • the object is irradiated with light in the longwave ultraviolet/visible part of the spectrum and the absorption spectrum of the object may be studied by measuring the intensity of light absorbed by the object.
  • the object may be illuminated with a lamp running off a mains electricity supply.
  • a change in the lamp supply voltage can alter the temperature of the emission source of the lamp and thus the spectral distribution of its output energy may vary. Provision should be made to detect this variation so that parameters such as ratios between transmitted wavelengths can be corrected for errors introduced by the spectral variation.
  • any spectral shift due to lamp variation can be detected and compensated for.
  • the absorption (or, equivalently, transmission) spectrum may be observed by measuring the absorption at 415.5nm and at least two slightly different reference wavelengths, say 410nm and 418.5nm.
  • the second embodiment of the first aspect of the invention allows all diamonds encountered to be classified as belonging to a class comprising definitely natural diamonds or a class containing diamonds which may or may not be natural. This will be explained further below.
  • the apparatus may be very simple to use and construct, as it only has a small number of components.
  • the whole apparatus may only occupy a space of about 25 x 10 x 15 cm, being suitable for use on a bench top.
  • the method does not require any great skill on the part of the operator and is suitable for producing an answer very quickly.
  • the second aspect of the present invention provides a method of and apparatus for classifying a diamond as definitely natural or not definitely natural as set out in Claims 36, 38, 44 or 45. Preferred and/or optional features of the invention are set forth in Claims 37 and 39 to 41.
  • a measurement of the absorption at 415.5nm is taken for the diamond and normalized on the basis of some parameter respresentative of the size of the diamond, for example the weight, or the absorption at at least one reference wavelength.
  • two or more reference wavelengths should be studied for the best results.
  • the absorption at 410nm and 418.5nm can be measured.
  • any spectral shift, due to illuminator variation can be detected and compensated for.
  • a single reference wavelength for example 410nm
  • spectral variations due to temperature variations of the lamp can be detected by sampling radiation directly from the lamp.
  • the invention also provides combined apparatus for performing any or all of the operations of the methods of the first and second aspects of the invention.
  • Figure 1 is a schematic side view of apparatus in accordance with the first embodiment of the first aspect of the invention
  • FIG 2 illustrates the bands passed by the two filters in Figure 1;
  • Figures 3a_ to 3c_ illustrate what occurs in figure 1 when a diamond with no luminescence is examined, showing the signal position, the no signal position, and the result of rocking;
  • Figures 4a_ to 4£ correspond, but show the situation for a diamond with luminescence
  • Figures 5a. to 5£ correspond, but show the situation with a diamond simulant without luminescence
  • Figures 6a and 6£ correspond, but show the situation with a diamond simulant with luminescence
  • Figure 7 shows an example of a portion of the absorption spectrum of type lb diamond
  • Figure 8 shows an example of a portion of the absorption spectrum of type IaAB diamonds
  • Figure 9 shows a high resolution transmission spectrum for a type IaAB diamond, between 410nm and 420nm;
  • Figure 10 shows an apparatus for observing a gemstone according to the second embodiment of the first aspect of the invention
  • Figure 11 shows the filter of the apparatus of Figure 12 in first and second positions
  • Figure 12 shows the variation with angle of incidence of band pass characteristics of the filter of Figures 10 and 11;
  • Figure 13 shows the use of three observations to fit a curve
  • Figure 14 is a schematic illustration of apparatus according to the second aspect of the invention.
  • Figure 15 shows an alternative embodiment of the second aspect of the invention.
  • Figure 16 shows a flow chart for use with the first or second and third aspects of the invention.
  • Figure 1 shows a stone 1 on a dop 2, the stone 1 being illuminated with a laser 3 which may be an argon ion laser operating a 514.5nm (shown as 9 in Figure 2), thereby stimulating luminescence of the stone 1 if the stone 1 is capable of it at the stimulating wavelength.
  • the stone 1 is viewed by eye through a laser blocking filter 4 which rejects light at laser wavelength (for example a Schott OG 530 rejects the laser light at 514.5nm) and a narrow band pass filter 5, for example a lnm FWHM 4 cavity design centred at 552.4 nm, manufactured by the Andover Corporation in the USA.
  • the narrow band pass filter 5 can be tilted about an axis 6 normal to its optical axis, and a drive 7 is shown for rocking or oscillating the filter 5.
  • the band passes of the narrow band pass filter 5 are shown in Figure 2, which shows graphs of transmissivity ⁇ against wavelength ⁇ for incident light parallel to and for incident light inclined to the optical axis of the filter 5.
  • the continuous lines indicate the bands passed when the filter is set up properly, normal to the optical or viewing axis.
  • the filter 5 passes a narrow band of about 1 nm (measured at the height of half maximum transmissivity), centered on the Raman emission (Stokes) at 552.4 nm. It can be seen that with this set-up a narrow band of detectable radiation wavelengths can pass - in this case, detectable radiation is radiation that can be detected by the eye.
  • the filter 5 can be set-up so that it is rocked from a first setting represented by the continuous line in Figure 2 to a second setting represented by the dashed line in Figure 2. This rocking can be done by hand, or, as indicated in Figure 1, by a motor drive 7.
  • Figures 3a.-3£ illustrate what occurs when the stone 1 is a non-luminescing diamond.
  • Figures 3a_ and 3b are graphs of ⁇ against ⁇ , while Figure 3£ is a graph of intensity i against time t.
  • the Stokes emission (illustrated as the peak in the emission 8) is passed when the filter 5 is in its first setting, and thus there is a signal (Figure 3 _).
  • Figure 3b When the filter 5 is in its second setting, the Stokes emission 8 is blocked and there is no signal ( Figure 3b).
  • Figure 3£ illustrate what occurs when the stone 1 is a non-luminescing diamond.
  • Figures 3a_ and 3b are graphs of ⁇ against ⁇
  • Figure 3£ is a graph of intensity i against time t.
  • the Stokes emission (illustrated as the peak in the emission 8) is passed when the filter 5 is in its first setting, and thus there is a signal (Figure 3 _).
  • Figure 3b When the filter 5 is in its second setting
  • the stone 1 is a diamond simulant with luminescence
  • the filter 5 in the first setting of the filter 5 there will be a signal.
  • the filter 5 is gradually moved from the first setting to the second setting, its band pass width slightly increases whilst its peak transmission drops slightly; in many cases, to a good first approximation the total integrated light transmission is unchanged and the total signal from the background luminescence spectrum is approximately constant.
  • the signal is as in Figure 6£.
  • a suitable photodetector 10 can be used.
  • the photodetector can be associated with processing equipment to distinguish between the types of signals shown in Figures 3 to 6 inclusive.
  • One way of classifying diamonds is according to their spe ⁇ troscopic properties.
  • the absorption spectrum of a diamond in the visible region will determine its colour.
  • An analysis of diamonds in this manner gives the following classification.
  • This general type class is defined as the class of diamonds which have a measurable defect induced infra-red absorption in the 1-phonon region (below 1332cm ).
  • the defects result from the incorporation of nitrogen atoms into the crystal lattice substituting for carbon atoms during growth of the diamond.
  • Natural type I diamonds will typically contain several hundred to a few thousand ppm of nitrogen.
  • the content of nitrogen in synthetic diamonds can be controlled during the process of synthesising the diamonds. This gives a range of nitrogen atom content of a few hundred ppm to practically zero in synthetic diamonds.
  • the general class type I is divided into the following subtypes:
  • Type lb diamonds represent a non-equilibrated form of diamond. Diamonds are formed at conditions of very high temperature and pressure, and if the diamond is maintained at these conditions impurity nitrogen atoms will tend to aggregate. Natural diamonds were usually maintained at these equilibrating conditions for geologically significant periods of time and accordingly type lb diamonds are rare in nature (much less than 1% of all natural diamonds). On the other hand, synthetic diamonds are not maintained at equilibrating conditions and accordingly most synthetic diamonds are type lb.
  • This class comprises diamonds in which the nitrogen has migrated to form more complex defects.
  • the A form comprises pairs of nitrogen atoms on nearest-neighbour substitutional sites.
  • the B form of nitrogen is believed to comprise a complex of four substitutional nitrogen atoms surrounding a vacancy.
  • the ratio of the concentration of A type defects to B type defects varies continuously, the extreme ends of the sequence being labelled type IaA and type IaB. Pure type IaB diamonds are very rare.
  • Synthetic type lb diamonds can be converted to type IaA by a high-temperature and high-pressure treatment.
  • Type IaA diamonds have no absorption in the visible region of the spectrum so they are colourless. There is very little visible absorption associated with B centres, and as a result IaB diamonds are colourless. Most natural diamonds contain both A and B centres and are known as type IaAB. In addition to the two principle forms of nitrogen defect, they contain two "by-products" of the nitrogen aggregation process: platelets and N3 centres. Platelets are interstitial planar defects, a few tens of nanometres in diameter lying on cube planes. These give rise to a peak in the infra-red spectrum. N3 centres comprise three co-planar nitrogen atoms probably surrounding a vacancy.
  • N3 centres give rise to absorption between 490nm and 350nm with a sharp zero-phonon line at 415.5nm.
  • This absorption in the blue/violet region causes the so-called cape yellow colour exhibited to a greater or lesser extent by the vast majority of natural diamonds (Figure 8).
  • Figure 9 is a high resolution transmission spectrum showing the 415.5nm absorption of a type IaAB diamond in more detail. It can be seen that there is a strong decrease in transmission at about 415.5nm, transmission being much higher at other wavelengths, for example 410nm.
  • This class comprises diamond in which nitrogen is only present in trace amounts, of the order of 1 ppm. There is often a form of background absorption at the shorter wavelength end of the visible spectrum, giving some of these diamonds a generally brown colour. This near absence of nitrogen in diamonds rarely occurs in nature (less than 2% of natural diamonds are type Ila) but can be assurred in the production of synthetic diamonds.
  • Type lib diamonds are generally natural, but synthetic diamonds containing added boron can be produced.
  • Figure 10 is a schematic drawing of apparatus according to the second embodiment of the first aspect of the invention, which is set up to classify a finished diamond as definitely natural or not definitely natural.
  • a diamond 12 is illuminated with radiation generated by a halogen lamp 13 of a suitable wavelength.
  • the illuminating radiation is fed to the diamond via a fibre optic 14 and, in the case of a brilliant cut diamond, the light is fed in through the table of the diamond.
  • a brilliant cut diamond is intended to be viewed through the table and is so shaped that the maximum amount of light is reflected by the lower faces of the diamond back out of the table 15.
  • a second fibre optic 16 is provided to collect light leaving the diamond via the table 15.
  • Transmitted light is fed via the fibre optic 16 into detector apparatus 17 which includes a filter 18.
  • a photomultiplier tube or other photodetector 19 is provided to give a signal dependent upon the intensity of light passed by the filter 18, which signal is fed to an amplifier 20 and then to a microprocessor 21.
  • the filter 18 is rotatable about an axis 25 to transmit light at different wavelengths. Rotation can be driven by a motor 22 or by hand.
  • the motor 22 can be controlled by the microprocessor 21, a transducer 23 comprising a shaft encoder or the like being provided to give a signal indicating the position of the filter 18.
  • a visual display unit (VDU) 24 may be provided receiving signals from the microprocessor 21.
  • the filter 18 can be rotated about an axis 25 normal to its optical axis 26 into a tilted position (as shown at 18' ).
  • the band pass characteristics of the filter 18 vary with the angle ⁇ between the optical axis 26 of the filter and the direction of incident light 27.
  • Such a filter is manufactured by Omega Optical Company in the USA.
  • the filter 18 is tilted through a variety of angles ⁇ by the motor 22, a region of the absorption spectrum of the diamond 12 may be scanned and sampled.
  • the apparatus shown in Figure 10 can be used to classify a diamond as belonging to type IaAB or not.
  • a filter 18 having the band pass characteristic shown in Figure 12 is used, so that a signal can be derived representive of the absorption of light at 415.5nm. On its own, this signal does not give much useful information unless it is normalized, because the signal will vary with the size of the diamond.
  • diamonds of type IaAB will vary greatly in the absorption co-efficient at 415.5nm between themselves, and no positive range can be assigned to clearly identify a diamond of type IaAB on the basis of this one uncorrected absorption signal alone. Accordingly, a second measurement is taken at a reference wavelength of 410nm for example.
  • the lamp 13 used to illuminate the diamond may be an halogen lamp, for example a 12 volt, 12 watt Thorn type M64 with a Spindler and Hoyer lens 063097.
  • This form of lamp operates at about 3, 000K with a peak in the middle part of the visible spectrum.
  • the wavelengths to be observed lie on a steep part of the thermal radiation curve. Accordingly, if the temperature of the lamp shifts to, say, 3, 200K due to a perturbation in the power supply, the shape of the curve will vary and the intensity of light at the wavelengths to be observed will vary quite markedly, the ratio of the intensities between the two irradiating wavelengths will vary, and so the reading based upon the intensity of radiation absorbed at these wavelengths by the diamond can be in error.
  • a third measurement may be made at a wavelength of, for example 418.5nm.
  • a whole series of measurements are made in the region 418.5 to 410nm, and the absorption results interpreted by a curve fitting technique, operated by the microprocessor 21 to detect if a 415.5nm absorption is in fact present.
  • the filter 18 is rotated at high speed (3,000 rpm) about its axis 25 and the absorption of light at various wavelengths (deducible from the angle ⁇ of the filter, measured by transducer 23) measured many times over and stored by the microprocessor.
  • high speed 3,000 rpm
  • the absorption of light at various wavelengths measured by transducer 23
  • a mass of data is obtained quickly and simply which can be analysed by a statistical technique to provide more accurate information on the absorption characteristics of the diamond. This improves the repeatability of the test and reduces the error.
  • the microprocessor 21 can be programmed to compare the readings directly and to produce a signal representative of whether the diamond is natural or should be tested further, or all the readings may be shown numerically, or graphically on the VDU 24.
  • Figure 13 shows how the three measurements at 410, 415.5 and 418.5nm can be used in the microprocessor to plot a curve showing the absorption characteristics of the diamond in this region of the spectrum, so that an absorption at 415.5nm can be clearly identified.
  • the spectrum of the lamp 13 may be sampled directly, using a reference channel.
  • a third fibre optic may be used, leading directly from the lamp 13 to a detector, which passes data to the microprocessor 21.
  • the apparatus of the invention can be set up as above, to divide all diamonds into one of two classes:
  • the number of natural diamonds classified in the second class by the apparatus of Figure 10 will be very small (about 2%), comprising type la, lb, Ila, lib and IaA or IaB diamonds, which are all very rare.
  • the apparatus of Figure 10 can also be used to measure the colour of a cape diamond, by measuring the strength of the 415.5nm absorption.
  • the lamp 13 may be a 12 volt 12 watt halogen lamp manufactured by Thorn, type M64, using a lens 063097 manufactured by Spindler and Hoyer Limited. Suitable fibre optic cable is manufactured by Schott.
  • the lenses shown in the detector 17 are, from left to right, a lens 063097 and lens 063045 respectively, both manufactured by Spindler and Hoyer.
  • the photomultiplier tube 19 can be of the type manufactured by Hamamatsu KK. ⁇ precede . , ⁇ - r ,- O 91/16617 23
  • Figure 14 shows apparatus for classifying a diamond according to the second aspect of the invention.
  • radiation is produced by a source 28 and fed into the system via mirror 29 through a wheel 30 having a broad band pass filter 30a for excluding infra red radiation or aperture 30b for controlling dynamic range.
  • the wheel 30 can be rotated by motor 31 to present a different aperture size 30c.
  • the radiation passes along a fibre optic system which has an input arm 32 and an output arm 33 in a similar manner to the arrangement of Figure 10.
  • the diamond 34 is irradiated with radiation and the transmitted radiation is collected by the fibre optic system and fed to a photomultiplier tube 36 through a narrow band pass filter 35a that passes radiation of wavelength 415.5nm.
  • the signal from the photomultiplier tube 36 is amplified at 37 and fed to a microprocessor 38 which can operate with a visual display unit 39.
  • second and third narrow band pass filters 35b and 35c of slightly different band pass characteristics say 410nm and 418.5nm, may be interposed between the diamond 34 and the photomultiplier tube 36 by rotating the filter wheel 35 using motor 31.
  • the filter wheel 35 may be rotated at high speed (for example 3, OOOrpm) to obtain a large number of measurements as in the apparatus of figure 10.
  • a signal representative of the absorption at the characteristic wavelength 415.5nm and at a reference wavelengths 410nm and 418.5nm can be obtained and compared.
  • the diamond is accordingly a type IaAB diamond and is classified as natural. Diamonds of other types do not give very different 415.5nm, 418.5nm and 410nm signals and are classified as possibly natural or possibly synthetic.
  • the lamp 28, the fibre optic cable 32, 33 and the photomultiplier 36 used in the apparatus Figure 14 may be the same as those used in the specific embodiment shown in Figure 10.
  • a Spindler and Hoyer mirror 29 may be used.
  • Figure 15 shows an alternative embodiment of apparatus for use with the second aspect of the invention, in which the reference numerals have the same meaning as in Figure 14 but only two narrow band pass filters are included in wheel 35, and only two absorption measurements are made.
  • An additional reference channel 40 is provided which directs light from the source 28 through the filter wheel 35 to the photomultiplier tube 36. Information can then be given directly to the microprocessor 38 on the spectral characteristics of the lamp 28 when a measurement is taken.
  • Figure 16 shows a flow chart for classifying a finished diamond using apparatus according to the first and second aspects of the invention.
  • the diamond is first analysed in terms of its colour at 41.
  • Two classes 42, 43 are produced, consisting of the following colour types (with their estimated o ⁇ curence, as a percentage, derived from intake figures for +0.5ct rough diamonds):
  • Diamonds of Class 1 are subjected to the 415.5nm test at 44 to produce a class of diamonds which are definitely natural (type IaAB) and a class of diamonds which are not definitely natural or 45 and 46. Class 2 diamonds are rejected as not definitely natural.

Abstract

Pour contrôler une pierre précieuse, on irradie la pierre et on l'observe à travers un filtre (5) sur une première longueur d'onde caractéristique d'une première catégorie de pierres précieuses. Le filtre peut être basculé depuis une position normale à l'axe optique pour transmettre des radiations d'au moins une longueur d'onde de référence. Les intensités des radiations transmises sur la première longueur d'onde et celle de référence sont observées et comparées de manière à pouvoir déterminer s'il s'agit d'une pierre de la première catégorie ou non. Pour déterminer si la pierre est un diamant ou une imitation, la première longueur d'onde comprend la caractéristique d'émission Raman du diamant. Pour déterminer si la pierre est naturelle de manière certaine ou incertaine, on classe la pierre comme étant naturelle de manière certaine s'il existe un maximum d'absorption de radiations à 415,5nm.
EP91907804A 1990-04-24 1991-04-24 Procede et appareil de controle d'un objet Expired - Lifetime EP0526492B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB909009132A GB9009132D0 (en) 1990-04-24 1990-04-24 Method and apparatus for examining an object
GB9009132 1990-04-24
PCT/GB1991/000653 WO1991016617A1 (fr) 1990-04-24 1991-04-24 Procede et appareil de controle d'un objet

Publications (2)

Publication Number Publication Date
EP0526492A1 true EP0526492A1 (fr) 1993-02-10
EP0526492B1 EP0526492B1 (fr) 2000-07-12

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EP91907804A Expired - Lifetime EP0526492B1 (fr) 1990-04-24 1991-04-24 Procede et appareil de controle d'un objet

Country Status (12)

Country Link
EP (1) EP0526492B1 (fr)
JP (1) JP2593267B2 (fr)
KR (1) KR0164426B1 (fr)
AU (1) AU660413B2 (fr)
CA (1) CA2081347C (fr)
DE (1) DE69132310T2 (fr)
GB (2) GB9009132D0 (fr)
HK (1) HK1006329A1 (fr)
IE (1) IE62169B1 (fr)
IL (4) IL97947A (fr)
WO (1) WO1991016617A1 (fr)
ZA (1) ZA913069B (fr)

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KR101424070B1 (ko) 2013-02-08 2014-07-28 전남대학교산학협력단 헤드 회전형 초음파 진단장치
GB2516297A (en) * 2013-07-18 2015-01-21 De Beers Centenary AG Measuring parameters of a cut gemstone
US10823680B2 (en) * 2016-08-26 2020-11-03 Public Joint Stock Company “Alrosa” Device for identifying a diamond
CN114467024A (zh) * 2019-08-05 2022-05-10 金展科技有限公司 钻石认证工艺以及用于钻石认证工艺的系统
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Also Published As

Publication number Publication date
JP2593267B2 (ja) 1997-03-26
GB2244329B (en) 1994-10-26
IL108478A0 (en) 1994-05-30
JPH05507791A (ja) 1993-11-04
GB9108733D0 (en) 1991-06-12
IE911368A1 (en) 1991-11-06
HK1006329A1 (en) 1999-02-19
KR0164426B1 (en) 1999-05-01
EP0526492B1 (fr) 2000-07-12
AU7693091A (en) 1991-11-11
IL97947A0 (en) 1992-06-21
CA2081347C (fr) 2002-06-11
GB2244329A (en) 1991-11-27
CA2081347A1 (fr) 1991-10-25
DE69132310D1 (de) 2000-08-17
IL108477A0 (en) 1994-05-30
AU660413B2 (en) 1995-06-29
GB9009132D0 (en) 1990-06-20
ZA913069B (en) 1992-02-26
DE69132310T2 (de) 2001-01-18
IL108513A0 (en) 1994-05-30
IL97947A (en) 1995-03-30
WO1991016617A1 (fr) 1991-10-31
IE62169B1 (en) 1994-12-28

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